ES2200280T3 - DISPERSION OF LAMINARY PIGMENT PARTICLES. - Google Patents

Abstract

SHEET PIGMENT PARTICLES ARE PRESENTED IN A FORMAT THAT IS EASILY USED FOR COVERAGE COMPOSITIONS TO BE USED IN A DISPERSION. THE DISPERSION CONTAINS THE PARTICLES OF THE PIGMENT IN AN AMOUNT THAT REPRESENTS 20 - 55% OF THE WEIGHT, AND ALSO INCLUDES A VEHICLE THAT IS COMPATIBLE WITH THE VEHICLE OF THE INTENDED COVERAGE COMPOSITION. THE DISPERSIONS ARE STABLE AND ESSENTIALLY ALLOW THE COMPLETE SEPARATION OF THE LAMINARY PIGMENT PARTICLES.

Description

Pigment particle dispersion laminar

Background of the invention

The present invention concerns dispersions of laminar pigment particles useful for the formation of coating compositions, i.e. paints containing metallic pigments, paints containing mica and others. Such paints are used, for example, for car coating,  plastics, cans and coatings industries in continuous, and for the realization of metal roofing and other coatings similar structural surfaces. The particles are usually use in the form of flake type.

Typically, to avoid stability problems and reduce shipping costs, laminar pigment particles for use in said coating compositions, they have been provided to the customer (i.e. the paint manufacturer or the final consumer) in the form of a highly concentrated paste. The paste is then mixed with a convenient vehicle to form the final coating composition.

However, in practice it has been difficult for the paint manufacturer or the final consumer form a paint with pigment paste, especially with pigment pastes finer Get the pasta to mix completely with the painting vehicle has usually required a lot of time and a relatively intense work. In addition, the difficulty in mixing the paste with the vehicle has resulted in the use of techniques mixed relatively hard, which can damage metal flakes, for example, by folding, curling or breaking them. Usually, the paste will be added to a tank that contains the vehicle of the paint or some component of it. As the pasta is added, the mixture is stirred with a Cowles propeller or paddle or Similary. Such procedures are not effective in separating paste particles, and can cause damage to the particles mentioned above, and you also need additional processing, such as filtering, to eliminate non dispersed particles. This causes problems such as lack of uniformity between different batches and less aesthetic properties desirable. It has also been found that pasta can be difficult to dispose of their containers, such as drums.

Background of prior techniques, such as WO94 / 28974, GB-A-2,156,828, US-A-5,104,922, US-A-4,081,423 and EP-A-0.154.679, describe compositions containing different amounts of particles of laminar pigments However, these antecedents are not addressed to the problem set forth in the present invention, and not take any action to offer adequate stability and uniformity to dispersions. For example, WO 94/28974 provides a product with a low level of products from the reaction or decomposition of fatty acid pigments. The Document GB-A-2,156,828 provides certain additives for the composition, to avoid defects of the Paint as lack of shine or veining. The document US-A-4,081,423 incorporates graphite to the coating composition to improve the properties of the lining and document EP-A-0.154.679 provides a basis Nitrocellulose free for nail polish.

In addition, the prior art background of the US-A-5,104,922 discloses a aqueous coating composition containing pigments of aluminum. This prior art background does not teach or suggest no particular aspect of the composition or procedure that is performed in accordance with the present invention, and does not take any measure to obtain the necessary stability of dispersions, what constitutes the main purpose of the present invention. Examples 1 and 2 of the document US-A-5,104,922, deal with the production of a "base preparation", in which the flakes of Aluminum are added in the middle or at the end of the process without adding No dispersion vehicle.

Summary of the Invention

The present invention seeks to overcome Disadvantages associated with the use of layered pigment pastes for the formation of coating compositions. In accordance with The present invention, the particles of laminar pigments are present in the form of a dispersion that contains 20-55% by weight of pigment particles laminar, having this dispersion of laminar pigments, a viscosity of 10,000 to 200,000 centipoise, measured with a Brookfield RVT viscometer, using a spindle number 7, at 5 rpm, as defined in claim 1.

The dispersion also includes a vehicle of dispersion that is liquid at room temperature, compatible with a vehicle for the formation of a coating composition. The laminar pigment particles are dispersed in the vehicle of dispersion and, preferably, can remain in a state dispersed, without separation, indefinitely, when the dispersion is stored at room temperature, although in some cases it can a fine sediment of the particles occur after approximately two weeks, which is acceptable.

The dispersion of the present invention is mixed easily with a vehicle for coating compositions, thereby reducing the time and work necessary to Make a coating composition. In addition, since they can used less hard mixing techniques, damage to particles of pigment can be reduced, thereby improving its consistency and aesthetic properties The need for equipment would be less, and it would take less time to work with these teams to make corrections in the lots. The dispersion can be Easily removed from containers such as drums. Besides, the dispersion of the present invention can improve the stability of storage, unlike pasta, especially for of non-film quality that are covered with fatty acids unsaturated Storage stability is highly dependent on the exposure of pigment particles to air. This exposure causes solvent evaporation and oxidation. of the lubricant, causing agglomeration of the flakes. The dispersions could also help exclude air while maintaining thus the integrity of the pigment.

Detailed description

The present invention offers a dispersion of laminar pigment particles for the formation of compositions of coating when mixed with a convenient vehicle. The Preferred laminar pigment is a metallic pigment, which is preferably, at least in part, aluminum, although, if desired, Other laminar pigments such as zinc, bronze, iron, mother of pearl and graphite The present invention is particularly useful for relatively thin scales, especially aluminum, for example particles whose average size is approximately 100 micrometers or less, especially 10 micrometers or less, since you are particles have a relatively high surface area and they can, in the form of paste, be difficult to mix with a vehicle for paint

The pigment particles can be in the form of film qualities or non-film qualities, although this invention can be particularly advantageous with qualities not films, whose fatty acid coverage tends to make them more susceptible to oxidation and agglomeration in the form of "welding cold ", to form undesirable lumps. Pigment particles in the dispersion of the present invention they are separated and protected, to some extent, by the presence of the vehicle of dispersion.

The amount of solid lamellar pigments in the dispersion is 20-55% by weight, preferably 40-50% Smaller amounts can be difficult to keep in suspension while larger amounts can tend to form a too doughy composition.

The dispersion also includes the vehicle of dispersion. The dispersion vehicle must be compatible with the laminar pigment particles. It must also be compatible with the vehicle of the coating composition with which it will be used. Thus, some dispersion vehicles must be chosen to be used with vehicles of compositions of aqueous coating, while others will be used as vehicles organic solvents of the coating composition.

In general, dispersion vehicles can Choose between plasticizers, solvents, resins and oils. Specific examples of resins include acrylic resins thermoformed, thermoplastic acrylic resins, resins alkyl, epoxy resins, polyester resins, resins hydrocarbons, melamine resins, phenolic resins, resins polyamides, silicone resins, styrenic resins, resins urea, urethane resins, and vinyl resins. Specific examples Plasticizers include phthalates such as dioctyl phthalate, diisodecylphthalate and butyl benzyl phthalate, alipates such as di-isobutyl adipate and diisodesil adipate, phosphates such as tricresyl phosphate and trioctyl phosphate, palstifiers Polymers such as polyester plasticizers and polyester adipate, epoxy plasticizers such as epoxidized soybean oil and octyl oleate epoxylated, citrates such as triethyl citrate, glycols such as butyl phthalyl butyl glycolate, and sebacatos as disebacato. Examples Solvent-specific include aliphatic hydrocarbons substituted and unsubstituted and aromatic hydrocarbons, for example  those with more than twenty carbon atoms, and solvents that they contain oxygen such as ketones, alcohols, glycol ethers, esters and nitroparaffins, for example those containing more than Twenty carbon atoms Specific examples of oils include animal, vegetable and synthetic oils such as flax, tung oil, castor oil, fish oil, oil Rapeseed, otic oil and soybean oil, fatty acids and others.

The dispersion vehicle may also contain rheological agents Some examples include montmorillonites, attapulgites, pyrogenic silicas, hydrogenated castor oil, high molecular weight polyolefins, calcium sulphonates and polyamides

The viscosity of the dispersion is generally of 10,000 to 200,000 centipoise, measured with a Brookfield viscometer RVT, using a spindle number 7, at 5 rpm.

The dispersion of the present invention shows stability. This means that the pigment particles laminar will remain scattered and not separated in position vertical. For the purpose of the present invention, it is considered that the dispersion shows sufficient stability if it is not separated to form a compact layer of laminar pigment particles at the bottom, and a clear layer (i.e., free of particles of laminar pigments) of the dispersion vehicle above, in position vertical for one year at room temperature. Particles of laminar pigments must be in the dispersion, completely separated in the liquid dispersion vehicle. Therefore it is it is preferable to form the dispersion using mixing equipment that offer a good low speed movement to the mix, with minimum damage to pigment flakes. More specifically, it is desirable to use a mixer that agitates the entire contents of the mixture with a enveloping movement The pallets of this device may be oriented vertically or horizontally, but must reach very close from the bottom and side walls of the mixing tank for reduce the formation of non-dispersed particles. The team it must also have variable speed, for example, up to 200 rpm, and should be able to operate at low speed, for example, at 3-25 rpm Other types of equipment can be used, but they might not be as efficient and could damage the particles of pigment.

The planetary double mixers are especially useful. For such devices, the speed of the paddles (i.e. the speed of rotation of each paddle on its same axis) should be approximately 5-35 rpm, preferably 12 rpm. Orbital speed (i.e. speed to which the vanes rotate around the mixing vessel) must be of about 3-25 rpm, preferably 10 rpm. Examples of mixing devices useful for the purpose of Present invention include the double PLM-5 planetarium and the PLM 150 double planetarium, from "Premier of Reading, PA ", 550 series mixers, which include the R550 / 500 and AG550 / 500, from "Myers Engineering of Bell CA", and the HDM-25 and HDM-200 from "Ross Engineering of Savannah, GA ".

To form the present dispersions, it is desirable to first add the particles of laminar pigments, by example in the form of paste, to the mixing device. It continues with the progressive addition of the dispersion vehicle to the device mixed, while mixing at a low speed, such as 3-25 rpm It is preferable that it not be added to the first mix more dispersion vehicle than the equivalent of about a quarter of the weight of pigment particles laminar After the first addition of the dispersion vehicle mixing should continue until the pigment particles Layers are completely moistened. If the particles do not they are completely wet, agglomerates or masses of scales attached to each other, which will hinder its complete dispersion in subsequent vehicle additions of dispersion.

It is necessary that the pigment particles laminar are essentially completely dispersed and separated in the dispersion. This can be evaluated from different ways. In one procedure, 10 grams of a dispersion of solids  Mix gently with 150 grams of a compatible solvent. The suspension obtained is then passed through a mesh light sieve 325. If no apparent mass is observed on the sieve, the separation can be considered complete. In another procedure, the dispersion is reduced to a solids level of 10% with a solvent or convenient vehicle. A coiled wire rod is used or Bird applicator to test the resulting paint on a Letter Morest or a glass panel. If no lumps or lumps are observed in the sample, the separation can be considered complete. In a third procedure, the paint obtained by the second procedure can be evaluated with a Hegman meter to determine the quality of the dispersion. While the acceptable reading for a dispersion may vary depending on the type of paint and size of the metallic pigment particles, typically, a reading of 7 or less will indicate an acceptable result for most coatings

The dispersion of the present invention can be packaged in cans or drums for shipment to the final consumer, for the formulation of coating compositions. Dispersion it can be used, and, in fact, in most cases it will be used more easily, with the equipment currently used to drive pigment pastes

The dispersion of the present invention can be "elongated", that is, converted into a composition of coating, through mixing with additional components of a coating composition, for example, a vehicle or resin, solvents, etc. On a small scale, this can be done manually using a spatula or a stirring device Similary. On a large scale, a propeller mixer can be used. In such a case, relatively low speeds can be used as 100-400 rpm

The present invention will be illustrated, additionally in the following non-limiting examples.

Example 1

In a Premier planetary double mixer with vertical vanes and a 11 liter mixing tank, are placed 2,000 grams of Super Fine Aluminum Paste "P" (medium size 7 micrometer particles), available at Silberline Manufacturing Co., Inc., of Tamaqua, PA. 200 are added slowly grams of flax oil while the vanes rotate at 12 rpm with a 10 rpm orbital speed. The paste / flax oil mixture is mixed for 25 minutes or until its appearance is homogeneous. The Paste attached to the walls of the tank or the vanes is agitated towards Mixing during mixing. After completing the mixing, you performs the subsequent addition of 300 and 380 grams of oil linen, following the same mixing parameters. Dispersion resulting has a metal solids content of 50% by weight and a viscosity in excess of 15,000 centipoise. Particles of Metallic pigments are completely separated and the dispersion is stable.

Example 2 *

Using the same equipment as in Example 1, placed 2000 grams of Super Fine Aluminum Paste in the tank "N", of Silberline Manufacturing Co., Inc. (average size of 5.5 micrometer particles). 300 grams of "Cymel are added 303 "(a melamine resin from Cytel Industries of West Patterson, NJ), while the paddles rotate at 12 rpm with a 10 rpm orbital speed. The mixture is mixed for 25 minutes or until its appearance is homogeneous. A second one is done and third addition of 600 grams each of the Cymel 303 resin, with an additional twenty minute mixing each time. This is followed for a fourth addition of 500 grams of Cymel 303 along with 500 grams of xylol and 300 grams of butanol, with a mixture of 15 minutes. The resulting dispersion has a metal content solids of 26.5% by weight, and a viscosity of 2,000 centipoise. The laminar pigment particles are completely separated and The dispersion is stable.

Example 3

The dispersion of example 1 can be used to form a coating composition with a coumarone resin inden, a mineral alcohol and cobalt, as follows.

A. 3,500 g of flax oil and 5,000 g are placed inden cumaron resin (CUMAR R-12, from Neville Chemical Company, Pittsburg, PA), in a hot mixing tank 20 liters The resin and flax oil are heated while they are agitated to solubilize the coumarron inden. After cooling it, it add, while stirring continuously with a mixer Ligthning at 150-200 rpm, 3,000 g of Varsol 1 (mineral alcohol, from Exxon), and the dispersion is slowly added of Example 1, while stirring continuously. It continues mixing for 15-20 minutes to ensure complete homogeneity. To this mixture is added, while stirring, 4,150 g of Varsol 1, 750 g of Aromatic 100 (a highly solvent Naphtha aromatic, Exxon), and 80 g of 6% cobalt (6% Cobalt Naphthenate, from Troy Corporation, East Hanover, NJ). The final paint is mixed for 15-20 minutes to ensure its homogeneity. The paint has a non-volatile content 53% by weight, an aluminum content of 2.75% by weight and a pigment binder content of 5.45% by weight. The flakes of aluminum remain essentially undamaged by the process of formulation.

B. They are placed in a hot mixing tank of 20 liters, 2,380 g of flax oil and 2,080 g of Nevchem 120 (hydrocarbon resin, from Neville Chemical Company, Pittsburg, PA). The hydrocarbon resin and flax oil are heated under stirring to solubilize the resin. The mixture is allowed to cool and  add 3,500 g of Varsol 1 while stirring. It continues mixing for 10 minutes and slowly adding 2,880 g of the aluminum dispersion of Example 1. After mixing for another 15 minutes to ensure homogeneity, 3280 g of Varsol 1 are added and 490 g of 6% cobalt, while stirring. It continues mixing for another 15-20 minutes to ensure their homogeneity, and the aluminum flakes remain essentially no damage by the formulation process.

Determinations are made with the meter Hegman in each paint to ensure that the aluminum flakes are They have dispersed completely and mixed. A reading of 6-7 is acceptable, and then the paintings can be applied with vaporizer for any final test or evaluation That is necessary.

Example 4 *

The dispersion of example 2 can be used For a paint composition as follows. They mix 78.2 kg of Chempol 11-2339 (high polyester resin Purity, from Cook Composites and Polymers, Port Washington, WI), 12.7 kg of methyl amyl ketone and 12.7 kg of Cymel 303. To the previous mixture it is aged, continuously stirring, 51.4 kg of the dispersion of the Example 2, 6.8 kg of xylol, 4.5 kg of methyl amyl ketone, and 3.6 kg of butanol Then a 1.9 kg premix of Nacure 1051 is added (Chempol resin catalyst from King Industries, Norwalk CT) and 7.3 kg of butanol. Then 0.4 kg of BYK 306 (an agent is added leveling fluid, from BYK-Chemie USA, Wallingford, CT) and mix for 20 minutes to ensure homogeneity. The resulting paint has a non-volatile content of 70.28% by weight, an aluminum content of 5.80% by weight, and a Pigment binder content of 12.00% by weight.

Determinations are made with the meter Hegman in the paint to ensure that the aluminum flakes have completely dispersed and mixed. A reading of 6-7 is acceptable, and then the paintings can be applied with vaporizer for any final test or evaluation That is necessary.

Comparative example one

880 grams of resin and solvent are placed in an 11 liter mixing tank that has a "Lightning Mixer "(a motor connected to a shaft with a propeller blade mixer). 2000 grams of Aluminum Paste are added slowly Super Fine "P", while the mixer rotates at 600 rpm. The suspension is mixed for two hours, after which it add additional solvent and resin to complete the paint. The paint sample has lumps and masses of aluminum paste not dispersed that need to be filtered.

Claims (23)

1. A dispersion of laminar pigments for form coating compositions containing pigments laminar, comprising:

20-55% by weight of laminar pigment particles, especially particles of metallic laminar pigments; Y

a dispersion vehicle for laminar pigment particles, being the vehicle of liquid dispersion at room temperature and compatible with a vehicle to form a coating composition;

said particles of laminar pigments being, essentially, dispersed completely and separated from each other in the dispersion vehicle, thus having a greater storage stability, and being easily mixable with said vehicle to form said coating composition, also reducing the time and work needed to perform the composition of coating; said dispersion of laminar pigments has a viscosity from 10 to 200 Pa-s (10,000 to 200,000 centipoises), measured with a Brookfield RVT viscometer, using a spindle number 7, at 5 rpm, being mostly obtained through the procedure according to one of the procedures of the claims 19 to 22 2. The dispersion of laminar pigments of the claim 1, wherein at least a portion of the particles of Laminar pigments is aluminum. 3. The dispersion of laminar pigments of the claim 1, wherein at least a portion of the particles of Laminar pigments is bronze. 4. The dispersion of laminar pigments of the claim 1, wherein at least a portion of the particles of Laminar pigments is zinc. 5. The dispersion of laminar pigments of the claim 1, wherein at least a portion of the particles of Laminar pigments is graphite. 6. The dispersion of laminar pigments of the claim 1, wherein at least a portion of the particles of Laminar pigments are pearly. 7. The dispersion of laminar pigments of a any one of claims 1 to 6, wherein the vehicle of dispersion is compatible with an aqueous vehicle for a composition Coating. 8. The dispersion of laminar pigments of a any one of claims 1 to 6, wherein the vehicle of dispersion is compatible with an organic solvent vehicle for a coating composition. 9. The dispersion of laminar pigments of a any one of claims 1 to 8, wherein the dispersion it has a viscosity of 10 to 90 Pa-s (10,000 to 90,000 centipoises), measured with a Brookfield RVT viscometer, using a spindle number 7, at 5 rpm. 10. The dispersion of laminar pigments of a any one of claims 1 to 9, wherein the vehicle of dispersion is at least one selected from the group consisting of plasticizers, solvents, resins, oils and agents rheological 11. The dispersion of laminar pigments of the claim 10, wherein the dispersion vehicle is at least one selected from the group consisting of acrylic resins thermoformed, thermoplastic acrylic resins, resins alkyl, epoxy resins, polyester resins, resins hydrocarbons, melamine resins, phenolic resins, resins polyamides, silicone resins, styrenic resins, urea resins, urethane resins and vinyl resins. 12. The dispersion of laminar pigments of the claim 10, wherein the dispersion vehicle is at least a plasticizer selected from the group consisting of phthalates, adipates, phosphates, polymeric plasticizers, plasticizers epoxy, citrates, glycols and sebacates. 13. The dispersion of laminar pigments of the claim 10, wherein the dispersion vehicle is at least a solvent selected from the group consisting of hydrocarbons substituted and unsubstituted aliphatic and aromatic, ketans, alcohols, glycol ethers, esters and nitroparaffins. 14. The dispersion of laminar pigments of the claim 10, wherein the dispersion vehicle is at least an oil selected from the group consisting of animal oils and Vegetables and fatty acids. 15. The dispersion of laminar pigments of the claim 10, wherein the dispersion vehicle comprises a rheological agent selected from the group consisting of montmorillonites, attapulgites, pyrogenic silicas, hydrogenated castor oils, high molecular weight polyolefins, calcium sulphonates and polyamides 16. The dispersion of laminar pigments of a any one of claims 1 to 15, wherein the size Average of the particles of laminar pigments is equal to or less than 100 micrometers 17. The dispersion of laminar pigments of a any one of claims 1 to 16, wherein the size Average of the particles of laminar pigments is equal to or less than 10 micrometers 18. The dispersion of laminar pigments of a any one of claims 1 to 17, wherein the particles of laminar pigments are presented in an essentially free state of agglomerations. 19. A procedure for the formation of a dispersion of laminar pigments suitable for the formation of a coating composition, comprising:

add pigment particles laminar to a mixing device;

add a vehicle from dispersion to the mixing device, which is compatible with a vehicle for a coating composition;

add the particles of pigment and dispersion vehicle so that the particles of pigment are completely moistened with the vehicle dispersion; and add and mix the additional dispersion vehicle to form a dispersion containing 20-55% in weight of laminar pigment particles; being preferably said laminar pigment particles and said dispersion vehicle, as defined in any one of the claims 1 to 18.

20. The method of claim 19, in that no more than about a quarter of the total dispersion vehicle used in the dispersion is added to the mixing device in the first addition.

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21. The method of claim 20, in which the mixing device is a mixing device through an enveloping action. 22. The method of claim 21, in which the mixing device is variable speed up to 200 rpm, and the first mixing stage is performed at no more than 25 rpm 23. A method of manufacturing a final coating composition by mixing the dispersion, as defined in any one of claims 1 to 18, with a vehicle suitable for forming a coating composition, said dispersion being preferably obtained by the process of one of the claims

 \ hbox {19 to 22.}